1. Field of the Invention
The present invention relates to a sensor equipped wheel support bearing apparatus equipped with a load sensor for detecting a load imposed on a bearing unit of a vehicle wheel and a vehicle control device which utilizes such sensor equipped wheel support bearing apparatus to perform a control of preventing movement of an vehicle in a direction counter to the direction of forward travel at the time of start of the vehicle on a grade.
2. Description of Related Art
As a technique to detect the load acting on each of the vehicle wheels of an vehicle, a sensor equipped wheel support bearing assembly has been suggested in, for example, the patent document 1 listed below, in which a strain gauge is pasted to an outer ring outer diametric surface of a wheel support bearing assembly so that the load can be detected from a strain induced in the outer ring outer diametric surface. Also, another suggestion has been made in the patent document 2 listed below in which a displacement detecting system in which an encoder is employed as a load sensor is employed in the sensor equipped wheel support bearing assembly capable of detecting the load inputted from a road surface. A sensor equipped wheel support bearing assembly has also suggested in the patent document 3 listed below, in which an influence of a braking force is compensated for by the utilization of a pressure developed in a brake cylinder. In addition, a sensor equipped wheel support bearing assembly has been suggested in the patent documents 4 and 5 listed below, in which in order to compensate for the influence brought about by the braking force, a sensor, which is separate from the load sensor, is employed for detecting the braking force acting on a caliper. Yet, although not intended to compensate for the influence brought about by the braking force, the patent document 6 listed below suggests a sensor equipped wheel support bearing assembly in which a plurality of sensor units are provided in a bearing fixed ring as strain detecting sensors so that the difference in amplitude of respective output signals of the sensor units that are disposed in face-to-face relation with each other can be determined to allow an input load to be estimated by classifying calculations according to situations by means a value thereof.
The patent document 7, for example, suggests mounting of a sensor unit, comprised of a strain generation member, which is fixed by means of three contact fixing segments, and two strain sensors mounted on the strain generation member, on an outer ring of a bearing assembly to thereby generate a single strain signal, so that an added value and an amplitude value and others of respective output signals of the two strain sensors are utilized as an output of the sensor unit to allow an estimating calculation process of an inputted load to be executed. Yet, a sensor equipped wheel support bearing assembly is suggested in which a displacement sensor (an eddy current sensor, a magnetic sensor, a reluctance sensor and others) is mounted on a stationary ring of the bearing assembly and a detection target is mounted on a rotatable ring of the bearing assembly and the amount of relative displacement of the inner and outer rings is then determined so that from the relationship between a preset load and the displacement the load then applied can be determined.
Although not associated with the wheel support bearing assembly, some vehicle control methods have been suggested in, for example, the patent documents 8 to 10 listed below, for minimizing a backward dragging of the vehicle at the time of the hill start of such vehicle. Specifically, the patent document 8 listed below discloses a technique employed in an electrically powered vehicle to properly control the creep torque at the time of parking of the vehicle, the patent document 9 listed below discloses a technique also employed in an electrically powered vehicle to control the start of a vehicle engine as necessitated by estimating a drive torque required to start, and the patent document 10 listed below discloses a technique to estimate a required clutch torque by measuring the gradient of a slope and then to release the brake with the required torque output. In addition to the foregoing patent documents, the patent document 11 listed below suggests an example of the specific control procedure to enable the vehicle to be operated with no delay in response to an input from a vehicle driver at the time of the start of the vehicle.